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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package com.sun.jmx.snmp.agent;

// java imports
//

import java.io.Serializable;
import java.util.Hashtable;
import java.util.Vector;

// jmx imports
//
import com.sun.jmx.snmp.SnmpVarBind;
import com.sun.jmx.snmp.SnmpStatusException;


/**
 * Represents a node in an SNMP MIB which corresponds to a group.
 * This class allows subnodes to be registered below a group, providing
 * support for nested groups. The subnodes are registered at run time
 * when registering the nested groups in the global MIB OID tree.
 * <P>
 * This class is used by the class generated by <CODE>mibgen</CODE>.
 * You should not need to use this class directly.
 *
 * <p><b>This API is a Sun Microsystems internal API  and is subject
 * to change without notice.</b></p>
 */

public abstract class SnmpMibGroup extends SnmpMibOid
    implements Serializable {

  // We will register the OID arcs leading to subgroups in this hashtable.
  // So for each arc in varList, if the arc is also in subgroups, it leads
  // to a subgroup, if it is not in subgroup, it leads either to a table
  // or to a variable.
  protected Hashtable<Long, Long> subgroups = null;

  /**
   * Tells whether the given arc identifies a table in this group.
   *
   * @param arc An OID arc.
   * @return <CODE>true</CODE> if `arc' leads to a table.
   */
  public abstract boolean isTable(long arc);

  /**
   * Tells whether the given arc identifies a variable (scalar object) in
   * this group.
   *
   * @param arc An OID arc.
   * @return <CODE>true</CODE> if `arc' leads to a variable.
   */
  public abstract boolean isVariable(long arc);

  /**
   * Tells whether the given arc identifies a readable scalar object in
   * this group.
   *
   * @param arc An OID arc.
   * @return <CODE>true</CODE> if `arc' leads to a readable variable.
   */
  public abstract boolean isReadable(long arc);


  /**
   * Gets the table identified by the given `arc'.
   *
   * @param arc An OID arc.
   * @return The <CODE>SnmpMibTable</CODE> identified by `arc', or <CODE>null</CODE> if `arc' does
   * not identify any table.
   */
  public abstract SnmpMibTable getTable(long arc);

  /**
   * Checks whether the given OID arc identifies a variable (scalar
   * object).
   *
   * @throws If the given `arc' does not identify any variable in this group, throws an
   * SnmpStatusException.
   */
  public void validateVarId(long arc, Object userData)
      throws SnmpStatusException {
    if (isVariable(arc) == false) {
      throw new SnmpStatusException(SnmpStatusException.noSuchObject);
    }
  }

  // -------------------------------------------------------------------
  // We use a hashtable (subgroup) in order to determine whether an
  // OID arc leads to a subgroup. This implementation can be changed if
  // needed...
  // For instance, the subclass could provide a generated isNestedArc()
  // method in which the subgroup OID arcs would be hardcoded.
  // However, the generic approach was preferred because at this time
  // groups and subgroups are dynamically registered in the MIB.
  //

  /**
   * Tell whether the given OID arc identifies a sub-tree
   * leading to a nested SNMP sub-group. This method is used internally.
   * You shouldn't need to call it directly.
   *
   * @param arc An OID arc.
   * @return <CODE>true</CODE> if the given OID arc identifies a subtree leading to a nested SNMP
   * sub-group.
   */
  public boolean isNestedArc(long arc) {
    if (subgroups == null) {
      return false;
    }
    Object obj = subgroups.get(new Long(arc));
    // if the arc is registered in the hashtable,
    // it leads to a subgroup.
    return (obj != null);
  }

  /**
   * Generic handling of the <CODE>get</CODE> operation.
   * <p>The actual implementation of this method will be generated
   * by mibgen. Usually, this implementation only delegates the
   * job to some other provided runtime class, which knows how to
   * access the MBean. The current toolkit thus provides two
   * implementations:
   * <ul><li>The standard implementation will directly access the
   * MBean through a java reference,</li>
   * <li>The generic implementation will access the MBean through
   * the MBean server.</li>
   * </ul>
   * <p>Both implementations rely upon specific - and distinct, set of
   * mibgen generated methods.
   * <p> You can override this method if you need to implement some
   * specific policies for minimizing the accesses made to some remote
   * underlying resources.
   * <p>
   *
   * @param req The sub-request that must be handled by this node.
   * @param depth The depth reached in the OID tree.
   * @throws SnmpStatusException An error occurred while accessing the MIB node.
   */
  @Override
  abstract public void get(SnmpMibSubRequest req, int depth)
      throws SnmpStatusException;

  /**
   * Generic handling of the <CODE>set</CODE> operation.
   * <p>The actual implementation of this method will be generated
   * by mibgen. Usually, this implementation only delegates the
   * job to some other provided runtime class, which knows how to
   * access the MBean. The current toolkit thus provides two
   * implementations:
   * <ul><li>The standard implementation will directly access the
   * MBean through a java reference,</li>
   * <li>The generic implementation will access the MBean through
   * the MBean server.</li>
   * </ul>
   * <p>Both implementations rely upon specific - and distinct, set of
   * mibgen generated methods.
   * <p> You can override this method if you need to implement some
   * specific policies for minimizing the accesses made to some remote
   * underlying resources.
   * <p>
   *
   * @param req The sub-request that must be handled by this node.
   * @param depth The depth reached in the OID tree.
   * @throws SnmpStatusException An error occurred while accessing the MIB node.
   */
  @Override
  abstract public void set(SnmpMibSubRequest req, int depth)
      throws SnmpStatusException;

  /**
   * Generic handling of the <CODE>check</CODE> operation.
   *
   * <p>The actual implementation of this method will be generated
   * by mibgen. Usually, this implementation only delegates the
   * job to some other provided runtime class, which knows how to
   * access the MBean. The current toolkit thus provides two
   * implementations:
   * <ul><li>The standard implementation will directly access the
   * MBean through a java reference,</li>
   * <li>The generic implementation will access the MBean through
   * the MBean server.</li>
   * </ul>
   * <p>Both implementations rely upon specific - and distinct, set of
   * mibgen generated methods.
   * <p> You can override this method if you need to implement some
   * specific policies for minimizing the accesses made to some remote
   * underlying resources, or if you need to implement some consistency
   * checks between the different values provided in the varbind list.
   * <p>
   *
   * @param req The sub-request that must be handled by this node.
   * @param depth The depth reached in the OID tree.
   * @throws SnmpStatusException An error occurred while accessing the MIB node.
   */
  @Override
  abstract public void check(SnmpMibSubRequest req, int depth)
      throws SnmpStatusException;

  // --------------------------------------------------------------------
  // If we reach this node, we are below the root OID, so we just
  // return.
  // --------------------------------------------------------------------
  @Override
  public void getRootOid(Vector<Integer> result) {
  }

  // -------------------------------------------------------------------
  // PACKAGE METHODS
  // -------------------------------------------------------------------

  // -------------------------------------------------------------------
  // This method can also be overriden in a subclass to provide a
  // different implementation of the isNestedArc() method.
  // => if isNestedArc() is hardcoded, then registerSubArc() becomes
  //    useless and can become empty.

  /**
   * Register an OID arc that identifies a sub-tree
   * leading to a nested SNMP sub-group. This method is used internally.
   * You shouldn't ever call it directly.
   *
   * @param arc An OID arc.
   */
  void registerNestedArc(long arc) {
    Long obj = new Long(arc);
    if (subgroups == null) {
      subgroups = new Hashtable<>();
    }
    // registers the arc in the hashtable.
    subgroups.put(obj, obj);
  }

  // -------------------------------------------------------------------
  // The SnmpMibOid algorithm relies on the fact that for every arc
  // registered in varList, there is a corresponding node at the same
  // position in children.
  // So the trick is to register a null node in children for each variable
  // in varList, so that the real subgroup nodes can be inserted at the
  // correct location.
  // registerObject() should be called for each scalar object and each
  // table arc by the generated subclass.

  /**
   * Register an OID arc that identifies a scalar object or a table.
   * This method is used internally. You shouldn't ever call it directly.
   *
   * @param arc An OID arc.
   */
  protected void registerObject(long arc)
      throws IllegalAccessException {

    // this will register the variable in both varList and children
    // The node registered in children will be null, so that the parent
    // algorithm will behave as if no node were registered. This is a
    // trick that makes the parent algorithm behave as if only subgroups
    // were registered in varList and children.
    long[] oid = new long[1];
    oid[0] = arc;
    super.registerNode(oid, 0, null);
  }

  // -------------------------------------------------------------------
  // registerNode() will be called at runtime when nested groups are
  // registered in the MIB. So we do know that this method will only
  // be called to register nested-groups.
  // We trap registerNode() in order to call registerSubArc()

  /**
   * Register a child node of this node in the OID tree.
   * This method is used internally. You shouldn't ever call it directly.
   *
   * @param oid The oid of the node being registered.
   * @param cursor The position reached in the oid.
   * @param node The node being registered.
   */
  @Override
  void registerNode(long[] oid, int cursor, SnmpMibNode node)
      throws IllegalAccessException {
    super.registerNode(oid, cursor, node);
    if (cursor < 0) {
      return;
    }
    if (cursor >= oid.length) {
      return;
    }
    // if we get here, then it means we are registering a subgroup.
    // We will thus register the sub arc in the subgroups hashtable.
    registerNestedArc(oid[cursor]);
  }

  // -------------------------------------------------------------------
  // see comments in SnmpMibNode
  // -------------------------------------------------------------------
  @Override
  void findHandlingNode(SnmpVarBind varbind,
      long[] oid, int depth,
      SnmpRequestTree handlers)
      throws SnmpStatusException {

    int length = oid.length;

    if (handlers == null) {
      throw new SnmpStatusException(SnmpStatusException.snmpRspGenErr);
    }

    final Object data = handlers.getUserData();

    if (depth >= length) {
      // Nothing is left... the oid is not valid
      throw new SnmpStatusException(SnmpStatusException.noAccess);
    }

    long arc = oid[depth];

    if (isNestedArc(arc)) {
      // This arc leads to a subgroup: delegates the search to the
      // method defined in SnmpMibOid
      super.findHandlingNode(varbind, oid, depth, handlers);
    } else if (isTable(arc)) {
      // This arc leads to a table: forward the search to the table.

      // Gets the table
      SnmpMibTable table = getTable(arc);

      // Forward the search to the table
      table.findHandlingNode(varbind, oid, depth + 1, handlers);

    } else {
      // If it's not a variable, throws an exception
      validateVarId(arc, data);

      // The trailing .0 is missing in the OID
      if (depth + 2 > length) {
        throw new SnmpStatusException(SnmpStatusException.noSuchInstance);
      }

      // There are too many arcs left in the OID (there should remain
      // a single trailing .0)
      if (depth + 2 < length) {
        throw new SnmpStatusException(SnmpStatusException.noSuchInstance);
      }

      // The last trailing arc is not .0
      if (oid[depth + 1] != 0L) {
        throw new SnmpStatusException(SnmpStatusException.noSuchInstance);
      }

      // It's one of our variable, register this node.
      handlers.add(this, depth, varbind);
    }
  }

  // -------------------------------------------------------------------
  // See comments in SnmpMibNode.
  // -------------------------------------------------------------------
  @Override
  long[] findNextHandlingNode(SnmpVarBind varbind,
      long[] oid, int pos, int depth,
      SnmpRequestTree handlers, AcmChecker checker)
      throws SnmpStatusException {

    int length = oid.length;
    SnmpMibNode node = null;

    if (handlers == null) {
      // This should be considered as a genErr, but we do not want to
      // abort the whole request, so we're going to throw
      // a noSuchObject...
      //
      throw new SnmpStatusException(SnmpStatusException.noSuchObject);
    }

    final Object data = handlers.getUserData();
    final int pduVersion = handlers.getRequestPduVersion();

    // The generic case where the end of the OID has been reached is
    // handled in the superclass
    // XXX Revisit: this works but it is somewhat convoluted. Just setting
    //              arc to -1 would work too.
    if (pos >= length) {
      return super.findNextHandlingNode(varbind, oid, pos, depth,
          handlers, checker);
    }

    // Ok, we've got the arc.
    long arc = oid[pos];

    long[] result = null;

    // We have a recursive logic. Should we have a loop instead?
    try {

      if (isTable(arc)) {
        // If the arc identifies a table, then we need to forward
        // the search to the table.

        // Gets the table identified by `arc'
        SnmpMibTable table = getTable(arc);

        // Forward to the table
        checker.add(depth, arc);
        try {
          result = table.findNextHandlingNode(varbind, oid, pos + 1,
              depth + 1, handlers,
              checker);
        } catch (SnmpStatusException ex) {
          throw new SnmpStatusException(SnmpStatusException.noSuchObject);
        } finally {
          checker.remove(depth);
        }
        // Build up the leaf OID
        result[depth] = arc;
        return result;
      } else if (isReadable(arc)) {
        // If the arc identifies a readable variable, then two cases:

        if (pos == (length - 1)) {
          // The end of the OID is reached, so we return the leaf
          // corresponding to the variable identified by `arc'

          // Build up the OID
          // result = new SnmpOid(0);
          // result.insert((int)arc);
          result = new long[depth + 2];
          result[depth + 1] = 0L;
          result[depth] = arc;

          checker.add(depth, result, depth, 2);
          try {
            checker.checkCurrentOid();
          } catch (SnmpStatusException e) {
            throw new SnmpStatusException(SnmpStatusException.noSuchObject);
          } finally {
            checker.remove(depth, 2);
          }

          // Registers this node
          handlers.add(this, depth, varbind);
          return result;
        }

        // The end of the OID is not yet reached, so we must return
        // the next leaf following the variable identified by `arc'.
        // We cannot return the variable because whatever follows in
        // the OID will be greater or equals to 0, and 0 identifies
        // the variable itself - so we have indeed to return the
        // next object.
        // So we do nothing, because this case is handled at the
        // end of the if ... else if ... else ... block.

      } else if (isNestedArc(arc)) {
        // Now if the arc leads to a subgroup, we delegate the
        // search to the child, just as done in SnmpMibNode.
        //

        // get the child ( = nested arc node).
        //
        final SnmpMibNode child = getChild(arc);

        if (child != null) {
          checker.add(depth, arc);
          try {
            result = child.findNextHandlingNode(varbind, oid, pos + 1,
                depth + 1, handlers,
                checker);
            result[depth] = arc;
            return result;
          } finally {
            checker.remove(depth);
          }
        }
      }

      // The oid is not valid, we will throw an exception in order
      // to try with the next valid identifier...
      //
      throw new SnmpStatusException(SnmpStatusException.noSuchObject);

    } catch (SnmpStatusException e) {
      // We didn't find anything at the given arc, so we're going
      // to try with the next valid arc
      //
      long[] newOid = new long[1];
      newOid[0] = getNextVarId(arc, data, pduVersion);
      return findNextHandlingNode(varbind, newOid, 0, depth,
          handlers, checker);
    }
  }

}
